test/studio.test.ts: a pull's preview case waits for the deploy it reads, and the file rejoins the gate #1165

The "Previews" cases in test/studio.test.ts now wait on their deploys and have much more timeout headroom. I could not run the file here, so none of this has been tested.

The sandbox refuses the unix-socket listen the test server needs (EPERM). Locally, 68 of 79 cases failed on that error in all three runs. test/check-list.test.ts passes, and the edited test file parses. The three-in-a-row runs and the full check still have to come from the forge's check on this push.

Cause (by reading the code): the "Previews" describe runs its AppsRuntime with concurrency: 1, so only one deploy runs at a time. The first case merges its pull and returns while the pull's deploy is being cut short and production's redeploy of main is queued. The next case then opens its pull and queues behind them. It polled envStatus for 30 s inside a 30 s test timeout, so on a loaded runner it was killed or failed at toBe("running").

Changes (test/studio.test.ts only):

• previewServes(record, env): it waits for the preview to reach running and has a 60 s limit. If it times out, the error names the state the preview reached, its error text, and the deploys still open. It replaces the polling loop in the "own copy" case. That was the only envStatus loop in the file.
• deploysIdle(): the first case now waits until the repo has no deploy open or queued before it ends, so the next case starts with a free slot.
• Timeouts: both cases go from 30 s to 120 s, which is 60 s of headroom over the longest wait.
• Assertions: they are unchanged.

Gate: test/studio.test.ts is already in GATE in scripts/gate.ts and not in EXCLUDED, so I left that file alone.

Closes #1044